336
AWUS01 KWNH 170316
FFGMPD
VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-MOZ000-ARZ000-170915-

Mesoscale Precipitation Discussion 0281
NWS Weather Prediction Center College Park MD
1115 PM EDT Fri May 16 2025

Areas affected...Portions of the OH/TN Valleys

Concerning...Heavy rainfall...Flash flooding possible

Valid 170315Z - 170915Z

SUMMARY...Strong to severe thunderstorms will continue into the
overnight hours across portions of the OH/TN Valleys, and will be
capable of also producing heavy rainfall totals. A combination of
cell-mergers and cell-training with moist antecedent conditions
will maintain a threat for scattered areas of flash flooding.

DISCUSSION...A well-organized severe weather outbreak continues to
unfold across areas of southern OH down through especially central
to southwest KY and northwest TN as a deep layer closed low
advances east across the upper Midwest and sends a cold front
southeastward into a very moist and unstable airmass.

MLCAPE values this evening remain locally quite high across
especially central KY through western TN with values of 2000 to
3000 J/kg in place. This strong instability continues to work in
tandem with enhanced shear profiles with 50 to 70+ kts of
effective bulk shear to support supercell convection with an
evolution into multiple linear bands/QLCS of activity over the
next several hours as the broader convective threat advances
eastward.

The onset of nocturnal cooling will be initiating a gradual
stabilization of the boundary layer and thus introducing some
low-level CINH, but the hires model guidance suggests some
intensification of the southwest low-level jet to as much as 50+
kts by 06Z. This should maintain a strong degree of moisture and
instability transport up across especially central and northern TN
through central and eastern KY that will be conducive for
maintaining a corridor of well-organized convection with heavy
rainfall rates.

Rainfall rates with the stronger and more organized cells will be
capable of reaching 2 inches/hour, and with some likelihood for
seeing cell-merger activity and cell-training, some additional
rainfall totals of 2 to 4 inches will be possible. This is
consistent with the 00Z HREF guidance, and it should be noted that
recent HRRR runs overall appear to be locally a bit underdone with
its QPF potential considering the high rainfall rates and
cell-training concerns.

The antecedent conditions across much of the region are quite
moist, and some areas saw heavy rainfall just within the last 12
to 18 hours. As a result, the additional rainfall amounts may
result in scattered areas of flash flooding overnight.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ILN...JKL...LMK...MEG...MRX...OHX...PAH...PBZ...
RLX...RNK...

ATTN...RFC...LMRFC...OHRFC...NWC...

LAT...LON   39848076 38698000 37528106 36408303 35738505
            35418803 35718965 36508976 37168760 37818589
            38548465 39618286